Vehicle lamps such as for example side flashing lamps or side marking or riding lamps frequently use bar-shaped light guides into which the light of a light source such as in particular an LED, is coupled at the end. Light guides have in particular the advantage that a desired light distribution can be implemented using relatively simple means and very inexpensively.
Reference will be made at this juncture to describe the structure and function of a typical vehicle lamp with a bar-shaped light guide in greater detail. FIG. 1 shows a side flashing lamp 4 which is known from the state of the art and which is integrated in an external rear view mirror 1 of a motor vehicle. In the present example the side flashing lamp 4 includes two bar-shaped light guides 5, 5′ which are arranged in mutually parallel superposed relationship and which extend substantially horizontally in the installed position on the vehicle. In operation light is coupled into the light guides 5, 5′ at the vehicle side which is to the left in FIG. 1, and the light is propagated as far as the oppositely disposed ends and is coupled out there. A part of the light also passes to the exterior (forwardly in the direction of travel) through a light exit opening 3 in the cover cap 2.
FIG. 2 shows a view in section taken along line II-II in FIG. 1. As can be seen therefrom, arranged at the end 10 of the light guides 5, 5′, which is the vehicle end, are light sources in the form of light emitting diodes 11 whose light is coupled into the light guides 5, 5′ in a longitudinal direction L. The major part of the light is passed by total reflection at lateral interfaces to a coupling-out end 7. In that situation a part of the light is scattered or deflected and, as mentioned, passes to the exterior through the light exit opening 3. The coupling-out end 7 has a bevelled coupling-out surface 8 whose inclination is so selected that the light which issues is emitted into a solid angular region which is prescribed by regulation, that is to say substantially transversely with respect to the direction of travel and somewhat inclinedly rearwardly, as is indicated by arrows F. In that respect the light emission region is determined by the direction of the light guide at the coupling-out end 7 and the inclination of the bevelled surface 8.
The region in which the LED 11 is arranged is covered over by a cover plate 14. If in addition further parts in the interior of the lamp casing are to be covered over, further cover plates have to be provided. Each additional plate however signifies an additional component which has to be produced and fitted.